Inflammatory Bowel Disease (IBD) is an umbrella term referring to two chronic diseases of the intestine both exhibiting chronic inflammation: Ulcerative Colitis and Crohn?s disease. Both diseases produce similar symptoms, and their pathogenesis still remains to be elucidated. The most popular theory is that IBD is caused by an overexpression of the immune system to a virus, bacteria and/or bacterial products. It is not yet known however whether these bacterial products can initiate the disease, exacerbate the existing disease or cause relapse. The objective of these experiments is to study the effects of bacterial peptides such as N-formylmethionyl-leucyl-phenylalanine (FMLP) in a reactivated model of colitis. This model more closely resembles the pathology of IBD than other models since it mimics the remission and relapse that is commonly found in the IBD patient. The specific aims of the proposed plan are to: 1) evaluate macroscopically and microscopically the degree of inflammation induced by FMLP in this model of colitis; 2) establish the role of important cytokines such as IL-4, IL-12, IFN-gamma and TNF-alpha in this reactivated animal model of colitis after the adminstration of FMLP; and 3) examine the effect of FMLP on intestinal transport in a reactivated animal model of colitis. The proposed research will contribute to our understanding of the pathogenesis of IBD and the role, if any, that FMLP plays in this disease. It will expand our general knowledge about the function that the intestinal microflora plays in the colon and ultimately offer insight into possible new therapeutic strategies.